The method is for storing subscriber-related data in communication systems having a plurality of subscriber connection networks.
Prior Art communications systems have non-redundant peripheral installations. These are for example connection installations for subscribers or for circuit lines that represent connections to other communications systems. In addition, communications systems have central installations that are at least duplicated due to requirements of reliability. These include, for example, the central control installation, coupling fields, protocol terminating installations, background memories and operating installations. All of these installations are single or multiple processor systems, controlled by software.
The peripheral installations fulfill essential switching-oriented tasks connected with the speech channels of the respective peripheral installation. They thus contain switching-oriented, operation and maintenance-oriented and administrative programs, as well as the data information associated with the installation. To the latter, there belong in particular subscriber-related data, such as data concerning the connection state, the signaling, the authorizations and call numbers. In addition, there belong hereto individual data with regard to connection lines, as well as data concerning the state of expansion and configuration of the peripheral installation. Thus, per 100 subscribers several megabytes of memory requirement can arise in the peripheral installations for the subscriber-related data just mentioned.
Modern subscriber connection networks are as a rule connected to the peripheral installations of the communications system via standardized interfaces, in Europe in particular via what are called V5 interfaces. There are up to three of what are called V5.2 communication channels (or C-channels) per PCM30 path of a V5.2 interface, which are provided in order to convey the central protocols as well as the PSTN signaling, the ISDN signaling and the ISDN D-channel packet data of administratively allocated V5.2 subscribers. The peripheral installations are connected among one another and with the common central control installation via a message distribution system, generally duplicated, which handles central and coordinating tasks. An interface to subscriber connection networks can have more than one PCM path (e.g. up to 16 PCM30 systems for V5.2 interfaces in full expansion), depending on the number of connected subscribers, as well as their traffic behavior. It is thus necessary in certain circumstances that a multiplicity of peripheral installations must be used for the preparation of such an interface in a communication system.
Since concentrating interfaces in particular, such as the V5.2 interfaces, have no fixed allocation between the subscriber and the speech channel of the interface to the communication system, a peripheral installation of the communication system must have access to the totalities of the subscriber data of those interfaces to subscriber connection networks that convey at least one PCM path to the relevant peripheral installations.
From the German patent application P 195 069 61.7, a method is known for the connection of V5.2 interfaces to the peripheral installations of a communication system. The connection thereby ensues in such a way that a failure of subscribers allocated to the interfaces, caused by a failure of a peripheral installation, can be avoided. This is achieved through the connection of one defined logical communication ring per V5.2 interface, which can be physically realized e.g. via the coupling field, and enables the intensive exchange of messages of the peripheral installations that conduct speech channels of the same V5.2 interface. The subscriber-related data of the subscribers connected via one of these interfaces are stored as an interface-specific totality in the peripheral installations that conduct speech channels of the interface. If a peripheral installation conducts speech channels of several interfaces, the several totalities of the subscriber-related data of these interfaces are stored in this peripheral installation. A problem with this way of proceeding is that each peripheral installation must keep ready considerable memory resources for the storing of the subscriber-related data.